High-Temperature Specific Heat of the TmBiGeO5 and YbBiGeO5 Compounds

The TmBiGeO5 and YbBiGeO5 compounds have been synthesized from Tm2O3 (Yb2O3), Bi2O3, and GeO2 oxides by the solid-state synthesis with successive burning at 1003, 1073, 1123, 1143, 1173, and 1223 K. High-temperature specific heat of the oxide compounds has been measured by differential scanning calorimetry. Basing on the experimental dependences Cp = f(T), the thermodynamic properties of the oxide compounds, i.e., the enthalpy and entropy variations, have been calculated.